1. Field of the Invention
The present invention relates to a robot hand which has a workpiece positioning function, a robot system, and a method of positioning and gripping a workpiece.
2. Description of the Related Art
When using various industrial robots to convey a workpiece, it is preferable that the workpiece should be gripped by the robot hand which is attached to the front end part of the arm, after being positioned in an accurate manner. In relation to this, JP-A-H6-182689 proposes the technique of using a positioning guide which is provided at a robot hand to guide the workpiece to be gripped to a regular position with respect to the hand. More specifically, the robot hand of JP-A-H6-182689 is provided with a suction head which can hold the workpiece so that it can be moved in the horizontal direction, and a cylinder which drives the suction head in ascending/descending directions, and is configured to lift the workpiece being held by the suction head so that it abuts against the guide, for the purpose of positioning. In this respect, the robot hand of JP-A-H6-182689 requires a mechanism for holding the workpiece so as to allow its movement in the horizontal direction, and a power source for driving the cylinder in ascending/descending directions, and therefore the robot hand becomes larger in dimensions and the manufacturing cost ends up increasing. Further, the robot hand of JP-A-H6-182689 uses the drive force of the cylinder to make the workpiece abut against a guide, and therefore the workpiece is liable to be deformed along with positioning.
A robot hand which is capable of accurately positioning and griping a workpiece without causing a deformation in the workpiece is being sought.